The present invention relates in general to pumps used for metering fluids. More particularly, the present invention relates to peristaltic pumps.
Many chemical dispensing systems utilize peristaltic pumps to supply chemicals in measured amounts. With industrial dish and clothes washers for example, peristaltic pumps meter the caustic and viscous chemicals used during the various wash and rinse cycles. The pumps typically include a length of flexible tubing and a rotatable spinner assembly having diametrically opposed rollers. The rollers press the inner walls of the tubing together at two points. As the spinner assembly is rotated, the rollers are moved along a curved section of tubing, forcing a measured amount of liquid through the tube. The required amount of a chemical may be delivered simply by operating the pump for a specific period of time.
Proper functioning of the peristaltic pump is dependent upon the ability of the spinner assembly to collapse the walls of the flexible tubing. The chemicals delivered with the chemical dispensing system often rapidly corrode the tubing. The continuous compression by the rollers wears down the flexible tubing, resulting in chemical leakage. Moreover, over time the tubing will harden, preventing the rollers from effectively squeezing the tubing wall. The flexible tubing must therefore be periodically replaced to ensure efficient and accurate operation of the peristaltic pump.
With available peristaltic pumps, replacement of the tubing is a complex, manually intensive and time consuming process which generally must be completed by a trained individual. The cover of the pump head must be removed, and the tubing disconnected from the input and output hoses and withdrawn from between the spinner assembly and the main body of the pump head. As the tubing is extracted from the pump head, any liquid remaining within the tubing is released. Depending upon the nature of the chemical, the spillage of excess liquid may be harmful and destructive in addition to creating a mess, potentially injuring the service individual and damaging nearby equipment. Since the maintenance is usually performed with the main body of the pump head installed for use, the required service often must be completed in awkward and inconvenient working conditions.
The present invention provides a peristaltic pump including a pump head designed as a removable cartridge. Instead of disassembling the pump head on site to remove the used flexible tubing, the entire pump head cartridge may be conveniently and efficiently replaced.
The spinner assembly must be freely rotatable and the rollers must completely collapse the tubing walls for efficient operation of the peristaltic pump. Many available peristaltic pumps are therefore designed having strict tolerance requirements, substantially increasing the cost of manufacture. Alternatively, various pumps include spring-loaded rollers for pressing the inner tube walls together while guaranteeing unrestricted rotation of the spinner assembly. The use of spring-loaded rollers increases the tolerances with which the peristaltic pump is designed. However, the spring-loaded rollers are more complex and higher in cost than other types of rollers.
The present invention provides a pump head cartridge which is not permanently mounted to the motor, but is instead secured so as to provide easy removal of the pump head from the motor. The cartridge housing is preferably formed of a material having some flexibility. With the flexible cartridge housing and the slight movement of the pump head during operation, a productive peristaltic pump may be manufactured under less restrictive tolerances.